UCLA Engineering: UCLA Engineer Fall 2004

Engineers Create Novel Energy Source for BioNano Devices
Proton Pump Encapsulated in Sol Gel

By Marlys Amundson

Materials science and engineering professor Bruce Dunn and bioengineering professor and chair Carlo Montemagno are combining their expertise in sol gel materials and nanoscale engineered devices to create a new type of solid material that generates protons when light shines on it. The material is a critical element in developing complex biological nanomanufactured systems.

“This technology will enable a lot of things when it’s complete,” said Montemagno. “We’re engineering living systems and need to be able to provide energy of the right type, the right size scale and in the right concentrations.”

Researchers in the UCLA Henry Samueli School of Engineering and Applied Science are encapsulating bacteriorhodopsin, which converts light into chemical energy, into a sol gel matrix. This new material will have the consistency of a soft contact lens.

“Bacteriorhodopsin is well known as a proton pump,” noted Dunn. “When light shines on it, protons are sent from one side of a membrane to the other.”

Dunn’s and Montemagno’s research groups are using this proton pumping mechanism in a variety of energy-related applications, including the generation of ATP.

Dunn, who holds the Nippon Sheet Glass Chair in Materials Science, has been creating biological-based materials since the early 1990s when he began collaborating with UCLA chemistry professor Jeff Zink to encapsulate various molecules in sol gel matrices.

Sol gel has the same chemical make-up as glass - silicon dioxide - and the same optical properties. Unlike glass, though, sol gel is porous and can be made at low temperatures. This property allows researchers to enclose, in a three-dimensional network, biological molecules which would otherwise decompose at high temperatures. The biological material may be nanosized, like proteins, but the sol gel material can be scaled in size for specific uses.

“We can encapsulate a wide variety of proteins and control the material’s chemical properties,” said Dunn. “The proteins are stabilized in the matrix, but retain and exhibit their natural properties.”

The new bacteriorhodopsin sol gel material serves as an innovative new energy source.

“Our work at the nanoscale is like building a new type of car,” explained Montemagno. “You first decide how you’re going to fuel it, which is ATP in our case, then you determine how you can provide the right type of fuel for the system.”

Dunn’s encapsulation method also allows researchers across UCLA to partner on a range of “designer” sensors for specific targets. For instance, in a collaborative project with researchers in the David Geffen School of Medicine, they have created an optical sensor to detect glutamate, a major excitatory neurotransmitter in the central nervous system.

In a project funded by NASA, Dunn’s lab is developing a sensor that measures cortisol levels for use in long-term space flights. Current methods of measuring cortisol levels, a hormone secreted in times of stress, are liquid based and cannot be used easily in zero gravity conditions. A sol gel sensor system would enable astronauts to measure their cortisol levels on-orbit, as part of a health monitoring protocol during space flight.

“There are a number of projects underway that merge multiple technologies,” said Montemagno. “Together, we’re transforming wet technologies to solid state technologies.”

For additional information on Dunn’s research, please visit http://www.seas.ucla.edu/ms/faculty1/dunn.html. For more on Montemagno’s research, please visit http://www.bioeng.ucla.edu/Facultyresearch/montemagno.html.